The filing comes as Fitbit is poised to launch an IPO, which it hopes will raise $100m (£65m). Jawbone recently obtained $300m (£195m) from investment fund BlackRock.

In a statement, Fitbit told us: “As the pioneer and leader in the connected health and fitness market, Fitbit has no need to take information from Jawbone or any other company. Since Fitbit’s start in 2007, our employees have developed and delivered innovative product offerings to empower our customers to lead healthier, more active lives. We are unaware of any confidential or proprietary information of Jawbone in our possession and we intend to vigorously defend against these allegations." ®